1. Field of the Invention
The present invention is directed to bicomponent reversible crimp filaments. More specifically, the present invention is directed to bicomponent, reversible crimp acrylic filaments which have improved dye uptake characteristics over prior art reversible crimp filaments and a bundle of such filaments.
2. Description of the Prior Art
Reversible crimp, bicomponent filaments are well known and desirable for use in fabrics because of their good bulk, cover, soft hand and resilience. These filaments are typically constructed of two fiber-forming polymeric components which differ in their respective abilities to shrink or swell upon exposure to a shrinking or swelling agent. These filaments are typically formed by extruding these two polymeric components through capillaries in a spinneret so that the resulting filaments have discrete, separate regions of each polymer along their lengths.
For example, bicomponent, reversible crimp filaments may be formed from polymeric components which have a marked difference in hydrophilicity due to differences in the amount of water-ionizable groups between the two components. After exposure to water, these filaments can be dried to develop a crimp, often helical in shape. The crimp decreases upon wetting and reforms upon drying; therefore, the crimp is said to be "reversible".
These types of filaments are disclosed in U.S. Pat. Nos. 3,038,238; 3,038,240; and 5,130,195. They have also been available commercially, for example, from Monsanto Company under the trade names PA-QEL.RTM. and REMEMBER.RTM. and from E.I. du Pont de Nemours and Co. previously under the designation SAYELLE.RTM. and more-recently under the trade name ORLON.RTM..
While the crimp reversibility of these fibers is their most attractive feature, they preferably also exhibit other characteristics which are desirable in fibers generally when used in textile applications. For example, as described in U.S. Pat. No. 3,065,042, shrinkage is of particular importance in the attainment of good fabric cover. Further, a rapid dye uptake rate for the fiber translates into increased dyed product manufacturing speeds.
Although the above commercial products have been successful, they have lacked some of the more general features mentioned above. For example, the REMEMBER.RTM. product, while exhibiting a relatively rapid rate of dying, also exhibits a degree of total shrinkage which, while acceptable, is improvable. The SAYELLE.RTM. DuPont-manufactured product, while exhibiting a highly desirable degree of total shrinkage and reversible crimp, also is characterized by a relatively slow dye uptake rate.
The need therefore exists for a bicomponent, reversible crimp filament which has a combination of high dye uptake rate and high degree of shrinkage and while maintaining the crimp reversibility and corresponding aesthetic qualities for which these types of fibers are noted.